the unerupted maxillary canine

Question 1

what is the prevalence of ectopic canines?

Answer 1

> 2% of the population

> palatally = 61%
line of arch = 34%
buccal = 4.5%

Question 2

what is the ratio of unilateral to bilateral ectopic canines?

Answer 2

> 4 : 1

Question 3

is ectopic canines more common in females than males ?

Answer 3

> females (70%)

Question 4

when are ectopic canines more likely to occur?

Answer 4

> when a patient has a class II div 2 malocclusion

Question 5

what is the primary problem of ectopic canines?

Answer 5

> it can cause root absorption of the adjacent tooth

Question 6

what tooth is most likely to be affected by root resorption by an ectopic canine?

Answer 6

> lateral incisor

> but can be multiple teeth (if lateral is missing, central is at risk)

Question 7

what is the best methods in measuring root resorption?

Answer 7

1. CBCT
2. CT
3. plane R/G (as 2D unable to fully show palatal resorption)

Question 8

why does an ectopic canine happen ?

Answer 8

> Crowding/shortening of arch length (common for buccal) (Jacoby, 1983)

> Adjacent lateral incisor missing or abnormal in shape or size

> Long path of eruption (Brin et al., 1986)

> Palatal = genetic; buccal = inadequate arch space

Question 9

what did the Brin et al study find on ectopic canines?

Answer 9

> 43 % of test subjects had absent or small incisors

> length of the root more critical than crown size as the root guides the canine into position

Question 10

what should you do if the canine is not palpable buccally at 9-10 years?

Answer 10

1. Check – bulge, inclination and colour of adjacent teeth.
2. Palpate – for the canine crown buccally and palatally, check for mobility of the 2 and C.
3. Radiographs – Presence, Position, Pathology (root resorption/ cyst formation)

Question 11

what is parallax radiograph technique?

Answer 11

> an apparent change in the position of an object resulting from a change in position of the observer.

> The principle of parallax can be used to determine the position of an unerupted tooth relative to its neighbours.

Question 12

when do we use the parallax technique?

Answer 12

> Dentists should be palpating for canines when a patient is 9-10 years old.

> Index of suspicion is raised if the pt has a missing, or abnormally shaped lateral incisor; has spaced arches, or if palpation indicates an asymmetrical eruption pattern

Question 13

what are the clinical signs of a palatally impacted canine?

Answer 13

> Delayed eruption of 3 or prolonged retention of the C

> Absence of normal labial 3 bulge or presence of a palatal bulge in the 3 region.

> Delayed eruption, distal tipping of migration of the lateral incisor.

> Loss of vitality and increased mobility of the central or lateral incisor

Question 14

why do we use the parallax technique?

Answer 14

> Knowing the location of the ectopic canine allows us to treatment plan more accurately.

> If not managed correctly an ectopic canine may resorb the root of the adjacent incisors. This may result in a medico-legal encounter.

Question 15

how do we take horizontal parallax?

Answer 15

> two IOPAs - at least 20 degrees of tube shift needed

> Anterior occlusal and an IOPA

Question 16

how do we take vertical parallax

Answer 16

> anterior occlusal and DPT

> IOPA and DPT

Question 17

how do you interpret parallax?

Answer 17

> if the canine moves with the beam its placed palatally , (the furthest away object will move with the beam) (with it pal)

> if it doesn’t move its in the line of arch

Question 18

what is better to use, horizontal or vertical parallax?

Answer 18

> In a study of 39 patients Armstrong et al. 2003 found that 69% of palatal ectopic canines were correctly located with VP, compared to 88% with HP.

> Both came back with 63% accuracy for buccal ectopic canines.

> The paper suggested that DPTs shouldn’t be used in the investigation of canine ectopia, where radiographs that allow the use of HP should be taken.

Question 19

what did the Ericsson & Karol study find out about ectopic canines?

Answer 19

> non crowded dentition

> extraction of deciduous canines yielded a 78% of self correcting an ectopic canine

> however If the lateral incisor root is in the way this greatly decreases the chance of self correction

Question 20

what did the power and short study find out about ectopic canines?

Answer 20

> crowded dentition

> removal of the deciduous canine yielded = 62% self corrected, 19% improved, 19% no change

> crowding reduced the dentition

Question 21

what did the Leonard et al find out about ectopic study?

Answer 21

> Longitudinal prospective controlled study

> Isolated extraction of C = 50% success

> Untreated control group = 50% success

> Creation of more space + extraction of C = 80% success

Question 22

when would you extract a deciduous canine in a patient?

Answer 22

> 10-13 years

Question 23

what do you have to consider when extracting a deciduous canine?

Answer 23

> consider the need for a balancing extraction

> it is better if there is no crowding

> consider the use of an URA or headgear to create space

> if no improvement in 12 months then other options should be considered

Question 24

why would you leave the decision of extraction of a deciduous canine to a specialist orthodontist?

Answer 24

> this will often be the treatment of choice

> however, ectopic canine may not be align-able and you may have extracted a highly useful tooth

> you’ll be left with a space if done wrong, always make a referral

Question 25

what patients are suitable for surgical exposure and orthodontic alignment?

Answer 25

> Willing to wear fixed appliances (good oral health)

> Well motivated and have good dental health

> Unsuitable for interceptive treatment

> Degree of malposition not too great

Question 26

what do you consider when judging the degree of malposition?

Answer 26

> apex position - how far is it from where you’d expect it to be?

> crown position - is the crown beyond the midline of the lateral incisor, is it beyond the of the central incisor or even has it regressed beyond the midline??

> angulation - the more inclined the longer the time

> the more malposition the tooth is the longer treatment will last and the less likely there will be success

Question 27

what are the 2 types of surgical exposure?

Answer 27

> open exposure

> closed exposure

Question 28

what is open exposure?

Answer 28

> overlying mucosa removed to expose the tooth,

> tooth can then be bonded to appliances

> (advantage is that the orthodontist can visualise better)

Question 29

what is a closed exposure?

Answer 29

> tooth is uncovered and a gold chain is attached, then the mucosa is put back in place. the gold chain is then attached to the orthodontic appliance and the forces pull the tooth threw.

> (you cannot see the canine)

> tends to be used when the tooth is farther away from the surface or an if an open exposure could cause damage to gingival tissue are adjacent teeth

Question 30

what is the impact on periodontal health between the open eruption and closed eruption? (Parkin et al)

Answer 30

> no evidence either method is superior

Question 31

what is the cost analysis of interceptive treatment in treatment of ectopic canines?

Answer 31

> only extraction of decidous canine

Question 32

what is the cost analysis of surgical exposure in the treatment of ectopic canines?

Answer 32

> Oral surgeon

> General anaesthetic

> 18 months of fixed appliance treatment

Question 33

what are the treatment options for an ectopic canine?

Answer 33

1. No treatment and observe long term for cystic change (cysts can absorb other teeth, after later teens this risk is reduced)
2. Interceptive treatment where appropriate
3. Exposure and alignment
4. Extraction
5. Transalveolar transplant or surgical repositioning

Question 34

what are the orthodontic treatment risk in ectopic canines?

Answer 34

> Risk of root resorption to adjacent teeth (lateral incisor and first premolar)

> Risk of pulpal obliteration to canine and adjacent teeth causing colour mismatch

> Risk of discontinued treatment due to prolonged treatment times

> Canine ankylosis, if other teeth move towards the canine in treatment this would suggest the canine is ankylosed

> High tendency to relapse

Question 35

what should you do if you identify an ectopic canine clinically or radiographically?

Answer 35

> Where canine ectopia is identified clinically or radiographically an urgent referral with copies of relevant radiographs should be sent to an orthodontic specialist